issue 6401/6661: combined proposal

Attached (or inlined as the case may be) is draft 6 of a proposal for 
issues 6401/6661. This proposal allows for the use of both the 
EventDescriptions element and Format-specific Notification WSDLs. There 
are still some open issues with this version of the proposal, but these 
can be worked out by the WG. Note that, as per our agreement at the last 
F2F, the section that describes the binding of wse:EventDescriptions to 
a Unwrapped Notification WSDL has been marked "TBD".

Thanks to Ram, Wu, and Li for their help and feedback. Thanks to their 
input I think we've got something in which the combination of 
EventDescriptions and Notification WSDLs offers some value beyond merely 
serving as a political compromise.

- gp